The present invention relates to a data format converter, and more particularly, to a data format converter for executing log conversion, antilog conversion, floating point conversion and inverse floating point conversion in an adaptive differential pulse code modulation (ADPCM) processor.
In general, an adaptive differential pulse code modulator is an element for extending channel capacity in an audio codec, a sound card, a digital signal processor and a wireless communication.
In order for an adaptive pulse code modulator to carry out ADPCM, a data format conversion of sign magnitude (SM) data, that is, log conversion, antilog conversion, floating point conversion and inverse floating point conversion should be executed.
That is, it may convert 16 bit SM data into log data and floating point data so as to execute ADPCM. And, it may execute antilog conversion for converting log data having a 4 bit exponent and a 7 bit mantissa into 16 bit SM data of a linear region.
In a prior art, complicate algorithms have been executed using a specific software routine of a general DSP chip.
For example, the following algorithm equation is used so as to convert said SM data into log data using software EQU log.sub.2 X=4.0(-0.3372223X.sup.2 +0.9981958X-0.6626105)
However, in case said algorithm is executed using software, software routine demands many macro codes and many hours for executing it are thereby required. It has a disadvantage in that the format conversion speed becomes slow.